Practical Organic Chemistry

PRACTICAL ORGANIC CHEMISTRY

separates as the sodium compound in the form of a semi-solid
mass. It is filtered and washed with a saturated solution of sodium
ethoxide in alcohol to dissolve out the /3-oxime. The product
is dissolved in water, saturated with carbon dioxide and
extracted with ether as before. Dry air is then drawn through
the liquid to remove the last traces of ether when, if pure,
the oxirne, on cooling to o°, solidifies. If not, it should be
distilled in i>acuo. At 12 mm. it boils at 122—124° : at lomm,
at 118—119°.
Yield, 10 grams.
-f- 3HO.,
C6H5.CHO + NH..OH.HC1 -f- zNaOH = C0H5CH:NONa + NaCi
C6HaCH:NONa + CO2 -f ILO = QH5CH:NOH + NaHC03.
Properties of a-Benzaldoxime.—Colourless needles, m. p.
34—35°-
Reaction.—Dissolve a small quantity of the a-oxime in a few
drops of acetic anhydride, warm if necessary, and cool quickly
by adding a little ice. Add to the clear solution solid sodium
carbonate and a little caustic soda solution. The solution
becomes clear on shaking or warming.
0-Benzaldoxime.—The various steps in the preparation
of the /3-oxime must be carried out continuously, and it is
therefore necessary to- be provided beforehand with about
300 c.c. of pure anhydrous ether.
The a-compound is dissolved in 50 c.c. pure dry ether, and
dry hydrogen chloride is passed in with constant shaking to
prevent the delivery tube from becoming blocked. Colour-
less crystals of the hydrochloride of the /3-oxime separate
and are filtered and washed with dry ether and then placed
in a separating funnel and covered with a layer of ether.
A concentrated solution of sodium carbonate is gradually added
with constant shaking until no further effervescence is observed.
Sodium chloride is precipitated and the /3-oxime dissolves in
the ether. The ether extract is separated, dehydrated over
sodium sulphate, and the ether removed as rapidly as possible
at the ordinary temperature by evaporation in vacua* The
residue crystallises, and when pressed on a porous plate leaves
a mass of small silky needles, m. p. 126—130°. It may be re-